The return of Orestes to avenge his father's death was good material for tragedy since it provided at any rate the possibility of a tragic dilemma. Thus in the Oresteia Orestes cannot deny the duty to avenge his father, a duty imposed by public opinion and divine command; but he cannot do this without killing his mother, an act that involves pollution and is also repugnant to the deepest instincts. In mythological terms he will inevitably be pursued either by the Erinyes of his father or by those of his mother. Aeschylus stresses the divine command, repeated at a crucial moment when Pylades breaks silence at Cho. 900, and presents Orestes as essentially guiltless, caught in a tragic dilemma, and eventually after much suffering purified and absolved. In Euripides the divine command is still there, though its validity is questioned both before and after the matricide, and Orestes is still faced with a dilemma, though he and Electra (who now becomes much more prominent) are presented in a less sympathetic light; in the main part of the play Euripides clearly invites us to condemn their action, and it is only in the epilogue that the mitigating circumstance of Apollo's command is emphasized and ultimate acquittal on Aeschylean lines is foreshadowed. In Sophocles the killing of Clytemnestra is approved even if not expressly commanded by Apollo, and it is not surprising that Orestes should be presented as justified. What has surprised many critics is that the dilemma seems to have disappeared: Orestes never has any doubts or qualms, nor indeed has anybody else in the play, and some have felt that this leaves Sophocles open to the charge of ‘moral obtuseness’. In 1927 J. T. Sheppard came to the rescue with an article entitled ‘In Defence of Sophocles’ (CR 41 (1927), 2–9) containing a new interpretation, which has now been revived and persuasively argued by J. H. Kells in his valuable edition of the play (Cambridge, 1973). Briefly it is that Sophocles is actually condemning the act of matricide quite as strongly as Euripides, not as explicitly but rather by means of ‘a series of subtle but forceful dramatic touches’, and that the play is ‘a continuous exercise in dramatic irony’. By this means Sophocles is inviting his audience not of course to condone the crime of Clytemnestra, but to condemn Orestes and Electra as murderers, and to see Electra, before the killing of her mother, as overwrought to the point of mental derangement and delusion, but ‘like many mad people hard-headed and cunning in achieving her ends’.